Plant Profile: Poison Hemlock

Whether foraging for greens or wildcrafting herbs, knowing the few toxic plants in one’s environment is essential. Poison hemlock is a potentially deadly plant that is frequently encountered in the forests and meadows of northern Arizona. This article and collection of photos is meant to help you identify this plant in your outdoor explorations and have a safe experience.

Botanical Name: Conium maculatum

Plant Family:
Apiaceae, formerly known as Umbelliferae. Common names for this family include the Carrot or Parsley Family

Common Name:
Poison Hemlock, this plant has no relation to the evergreen Hemlock tree.
Other names include Deadly Hemlock, Poison Parsley, Spotted Hemlock, European Hemlock, and California or Nebraska fern

Identifying Characteristics (see photos):
The stalk is hairless with purple blotches on a green background.
All the stalks in this family are hollow. Some human poisoning occurs from using the dried Conium stems as a play whistle.
Leaves are fern-like and resemble carrot or parsley leaves.

Habitat:
In the Flagstaff area, it is found in disturbed soil with a bit of extra moisture. It is found in open fields, on hillsides and in open areas of the ponderosa forest.

Height:
Depending on growing conditions, it can reach any height up to 8’. Newer plants often are 12″ or less in height.

Possible Look – A – Likes Around Flagstaff:
Queen Anne’s Lace (Daucus carota) rarely reaches higher than 3’ in height and flowers later in the summer: mid July through August. Conium flowers late spring through late June.

Toxic Chemistry:
The toxic compounds are coniine, gamma-coniceine, and various piperidine alkaloids.
All parts of the plant are poisonous. Even the dead stalks remain dangerous. Eating the plant is the most dangerous but it can also be toxic through the skin and lungs.
This plant is also toxic to livestock. Call a veterinarian immediately if poisoning is suspected.

What to Do if Poisoned:This plant can be deadly. Do not delay getting medical help. The sooner medical help arrives the better. Call 911.